The idea of the Rock being the CONFESSION Peter made and not being Peter himself is definitely well-attested in the early church. Augustine stands out as one of the main proponents of the idea of the confession being the Rock:
Peter then was true; or rather was Christ true in Peter? Now when the Lord Jesus Christ would, He abandoned Peter, and Peter was found a man; but when it so pleased the Lord Jesus Christ, He filled Peter, and Peter was found true. The Rock (Petra) made Peter true, for the Rock was Christ– St. Augustine, A Library of the Fathers of the Holy Catholic Church (Oxford: Parker, 1845), Volume 20, Sermon 97.3, p. 686, (Sermon 147, Benedictine Edition).
Peter had already said to him, ‘You are the Christ, the Son of the living God.’ He had already heard, ‘Blessed are you, Simon Bar-Jona, because flesh and blood did not reveal it to you, but my Father who is in heaven. And I tell you, that you are Peter, and upon this rock I will build my Church, and the gates of the underworld shall not conquer her’ (Mt 16:16-18). Such faith was drowned when the Lord was crucified. Peter, you see, only believed he was the Son of God up to the time he saw him hanging on the tree, the time he saw him fixed there with nails, the time he saw him dead, the time he saw him buried. Then he lost what he held. Where’s the rock? Where’s the immovable solidity of the rock? Christ himself was the rock, while Peter, Rocky, was only named from the rock. That’s why the rock rose again, to make Peter solid and strong; because Peter would have perished, if the rock hadn’t lived–St. Augustine, John Rotelle, Ed., The Works of Saint Augustine (New Rochelle: New City, 1993) Sermons, Volume III/7, Sermon 244.1, pp. 95-96.
I wish to make a post here in respect to the OP, not to engage in differences between Orthodox opinions but to clarify here, That this Roman Catholic St.Augustine is not recognized by most Orthodox Churches who are not in communion with Rome because of his loyalty to the Catholic magisterium. Then To try and use his writings against his Catholic beliefs and try and persuade that he “Augustine” holds to a protestant view of Peter and Rock from his “confession” reveals a lack of understanding of St. Augustines thought and writings.
St.Augustine writings never contradict themselves. These writings never deal with Peter’ confession being the rock, but are dealing with the faith of Peter, not Simon bar Jona who made the confession of Jesus being the Son of God, Peter never makes this confession from Mt.16. Jesus begets Peter by changing Simon bar Jona’s name.
Had Jesus built his Church upon a confession that revealed him to be the Son of God? Jesus would of built his church upon Nathanael, for he was the first disciple to reveal His (Jesus) divinity from John 1:49, not to mention the centurion’s whom Jesus found the greatest faith in all of Israel. No the confession was from Simon bar Jona never Peter which was a sign from heaven, whom God chose for Jesus to begin building his Church upon the (rock = Kephas) = Peter. Then Later God reveals to Peter from heaven to allow the Gentiles into His Church.
I must confess, I am not here to dispute orthodox opinions, but to correct a misquote from a Catholic Saint Augustine from Hippo. Here is ST. Augustines official teaching on (Rock) Matthew 16… which never conflicts with the above quotes by St. Augustine. And the Orthodox know this.
ST. Augustine (To Generosus letter No. 53)
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For if the order of succession of bishops is to be considered, how much more surely, truly and safely do we number them from Peter, to whom, as representing the whole Church, the Lord said; “Upon this rock I will build my church and the gates of hell shall not prevail against it” (Mt. 16:18). For, to Peter succeeded Linus, to Linus Clement, to Clement Anacletus, to Anacletus Evaristus, to Evaristus Sixtus, to Sixtus Telephorus, to Telephorus Hyginus, to Hyginus Anicetus, to Anicetus Pius, to Pius Soter, to Soter Alexander, to Alexander Victor, to Victor Zephrinus, to Zephrinus Calistus, to Calistus Urban Pontian, to Pontian Antherus, to Antherus Fabian, to Fabian Cornelius, to Cornelius Lucius, to Lucius Stephen, to Stephen Sixtus, to Sixtus Dionysius, to Dionysius Felix, to Felix Eutychian, to Eutychian Gaius, to Gaius Marcellus, to Marcellus Eucsbius, to Eucsbius Melchiades, to Melchiades Sylvester, to Sylvester Marcus, to Marcus Julius, to Julius Liberius, to Liberius Damasus, to Damasus Siricius, to Siricius Anastius”…
Peace be with you